unable to see the gdm login screen in maverick some thing broke

[Tapas Mishra]

Hi,
today I installed nfs-kernel-server,nfs-common,portmap
then I had updated 10.10 which was already running
with do-release-update -d
some thing really got updated what I see is I am unable to get the
gnome login screen.
ps -el does not shows gnome running.
Though I do see a black screen on which I can just login.
I tried startx :1
startx :-1,
/etc/init.d/gdm start
/etc/init.d/gdm restart
all these attempts went in vain.
What do I need to be able to get back the screen.
Every thing was working fine until after noon.